JP2002356503A - Method for producing vinyl polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a vinyl polymer whereby the small molecular weight vinyl polymer having a weight average molecular weight of 5,000 or less can be surely obtained and the vinyl polymer having a terminal double bond with high rate can be obtained. SOLUTION: The vinyl polymer is produced by polymerizing of a monomer mixture containing 2,4-diphenyl-4-methly-1-pentene and other vinyl monomer such as a styrene, acrylate at a polymerization temperature of >220 deg.C and <=350 deg.C. Preferably, contents of 2,4-diphenyl-4-methly-1-pentene are 1-20 mass% and that of other vinyl monomer is 80-99 mass% in the mixture. The polymerization is preferably carried out using a continuous stirring tank type polymerization reactor under controlling the polymerization reactions in stable states.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a vinyl polymer having a very small molecular weight.

[0002]

2. Description of the Related Art Conventionally, as a method for obtaining a low molecular weight vinyl polymer, α-methylstyrene dimer (chemical name: 2,4-diphenyl-4-methyl-1-pentene) has been used.
There is known a method for producing a vinyl polymer in which another vinyl monomer is polymerized in the presence of a polymer. In this conventional method, specifically, polymerization is performed at a polymerization temperature of 200 ° C. or less.

[0003]

However, when the polymerization is carried out at a polymerization temperature of 200 ° C. or lower, the molecular weight is reduced to some extent, but the decomposition of the polymer radical is not sufficient, so that the weight (mass) average molecular weight is 5,000. It has been difficult to reliably obtain a vinyl polymer having the following extremely low molecular weight. In addition, for the same reason, there is a problem that the ratio of the obtained vinyl polymer having a double bond at a terminal is small.

The present invention has been made by focusing on the problems existing in the prior art as described above. The object is to obtain a vinyl polymer having a weight average molecular weight of 5,000 or less and a vinyl polymer having a double bond at the end and a vinyl polymer having a large ratio of double bonds at the terminal. An object of the present invention is to provide a method for producing a polymer.

[0005]

In order to achieve the above-mentioned object, a method for producing a vinyl polymer according to the first aspect of the present invention comprises a method for producing 2,4-diphenyl-4-methyl-1-pentene and other compounds. A monomer mixture containing a vinyl monomer,
The polymerization is carried out at a polymerization temperature of more than 20 ° C and not more than 350 ° C.

According to a second aspect of the present invention, there is provided the method for producing a vinyl polymer according to the first aspect, wherein the content of 2,4-diphenyl-4-methyl-1-pentene in the monomer mixture is adjusted. Is 1 to 20% by mass, and the content of other vinyl monomers is 80 to 99% by mass.

According to a third aspect of the present invention, there is provided a method for producing a vinyl polymer according to the first or second aspect, wherein the vinyl polymer is a vinyl polymer based on the number of molecules of the vinyl polymer. Has an average value of 0.7 to 1.0 of the number of double bonds at the terminal.

According to a fourth aspect of the present invention, in the method for producing a vinyl polymer according to any one of the first to third aspects, the polymerization is carried out using a continuous stirred tank type polymerization vessel. It is something to be done.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. The vinyl polymer in the embodiment,
A monomer mixture containing 2,4-diphenyl-4-methyl-1-pentene and other vinyl monomers was added to 220
It is manufactured by polymerizing at a polymerization temperature of over 350C to 350C.

2,4-diphenyl-4-methyl-1-pentene is 2-methylstyrene (α-methylstyrene)
And a monomer used as a polymerization degree regulator or the like when a vinyl monomer is polymerized.

The other vinyl monomers are the main monomers for obtaining the desired vinyl polymer.
As this vinyl monomer, in addition to the acrylic monomer,
Styrene, vinyl acetate, acrylonitrile and the like are used. Examples of the acrylic monomer include an acryloyl group-containing monomer and a methacryloyl group-containing monomer, and specific examples include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acrylic acid, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, (meth) acrylic acid Glycidyl and the like. In this specification, (meth) acryl means acryl or methacryl. One or more of these monomers are appropriately selected and used.

In order to obtain an acrylic polymer as the vinyl polymer, it is preferable that the ratio of the acryloyl group-containing monomer unit in the vinyl monomer is 70% by mass or more. If the proportion of the acryloyl group-containing monomer unit is less than 70% by mass, good weather resistance cannot be imparted to the vinyl polymer, and coloring tends to occur.

2,4-diphenyl-4 in the monomer mixture
The content of -methyl-1-pentene is preferably 1 to 20% by mass, and the content of other vinyl monomers is 8%.
It is preferably from 0 to 99% by mass. When the content of 2,4-diphenyl-4-methyl-1-pentene is less than 1% by mass, that is, when the content of the vinyl monomer exceeds 99% by mass, the chain transfer efficiency during the polymerization of the monomer decreases. . On the other hand, when the content of 2,4-diphenyl-4-methyl-1-pentene exceeds 20% by mass, that is, when the content of the vinyl monomer is less than 80% by mass, 2,2
4-diphenyl-4-methyl-1-pentene remains,
It is difficult to remove it, and there is a tendency that the vinyl monomer is reduced and production efficiency is deteriorated.

The polymerization reaction is carried out at a polymerization temperature of over 220 ° C. and up to 350 ° C., preferably at a polymerization temperature of 230 to 350 ° C. By conducting a polymerization reaction at such a high temperature, a vinyl polymer having an extremely small weight average molecular weight and a large proportion of those having a double bond at a terminal can be obtained by efficiently causing an addition-cleavage type chain transfer reaction. Moreover, the polymerization can be carried out without substantially using a polymerization initiator or another chain transfer agent. Therefore, it is possible to avoid the influence of residues and decomposition products derived from the polymerization initiator and the chain transfer agent. As a result, the vinyl polymer can exhibit excellent weather resistance, and can also suppress generation of coloring and odor.

When the polymerization temperature is 220 ° C. or lower, it is difficult to obtain a vinyl polymer having a very small weight average molecular weight and a large proportion of those having a terminal double bond. Moreover, polymerization requires a polymerization initiator and a chain transfer agent,
In this case, the vinyl polymer is colored or odors are generated, and the weather resistance is reduced. On the other hand, when the polymerization temperature is 3
When the temperature exceeds 50 ° C., a decomposition reaction is likely to occur in the vinyl polymer, and coloring may occur. In order to perform polymerization more efficiently, a small amount of a polymerization initiator or a chain transfer agent may be used. When used, the concentration is preferably 1% by mass or less. Examples of such a polymerization initiator include ditertiary butyl peroxide, benzoyl peroxide, and azobisisobutyronitrile, and examples of the chain transfer agent include dodecyl mercaptan.

The polymerization method is preferably a bulk polymerization method or a solution polymerization method. Specifically, it is preferable to use a continuous stirring tank type polymerization vessel and perform the stirring continuously while stirring in the stirring tank. By adopting such a polymerization form, the control of the polymerization reaction is facilitated, and the polymerization reaction is maintained in a stable state, whereby a vinyl polymer can be obtained.

The 2,4-diphenyl-4-methyl-1-pentene may be supplied from a raw material tank to a polymerization vessel together with other vinyl monomers as one component of the monomer mixture, or may be obtained by other methods. May be supplied to the polymerization vessel. Other methods are exemplified below.

When the raw material vinyl monomer mixture contains styrene, the reaction liquid extracted from the polymerization vessel is introduced into a thin-film evaporator, and 2,4-diphenyl-4-tetrafluoro-4-ether is included in the volatile components recovered. Methyl-1-pentene may be included. In such a case, 2,4-diphenyl-4-methyl-1-pentene can be supplied by supplying the recovered volatile component as it is or by concentrating it to the polymerization reactor.

A vinyl polymer obtained as described above,
That is, the macromonomer is 2,4-diphenyl-4-
The polymer radical to which methyl-1-pentene is added is 22
Since it is easily cleaved at a high temperature exceeding 0 ° C., the weight-average molecular weight is extremely small, ie, 5,000 or less.
Further, the average value of the number of double bonds at the terminal of the vinyl polymer based on the number of molecules of the vinyl polymer is 0.7 to 0.7.
1.0 is obtained. When the average value is less than 0.7, the number of double bonds is small, and the graft efficiency when a vinyl polymer is copolymerized with a vinyl monomer decreases. On the other hand, since the average value is 1.0, which is the theoretical upper limit, it does not usually become larger. That is, in the vinyl polymer, there are those having a double bond at one end, those having a double bond at both ends, and those having no double bond. The upper limit is 1.0
Becomes However, due to measurement errors and special polymerization conditions, 1.0
May be exceeded.

Since the vinyl polymer obtained by the method of the present invention has a double bond at the terminal, a graft copolymer can be obtained by radical copolymerization with a vinyl monomer according to a conventional method. . In this graft copolymer, a polymer portion formed from a vinyl monomer becomes a trunk component, and a polymer portion formed from other vinyl monomers in a vinyl polymer (macromonomer) becomes a branch component. . As the vinyl monomer, the other vinyl monomers described above can be used. Since the ratio of the vinyl polymer of the present invention having a double bond at a terminal is large, a graft copolymer can be efficiently obtained when the vinyl polymer is copolymerized with a vinyl monomer. That is, the graft ratio in the graft copolymerization increases.

In addition, since the molecular weight distribution of the vinyl polymer can be reduced, it is excellent in plasticity, and the surface of a molded product formed from the vinyl polymer is hardly tacky. Further, the vinyl polymer is preferable because it has a double bond at the terminal, and hence the surface of the molded article is less likely to be sticky.

Accordingly, vinyl polymers are suitably used as flow modifiers and plasticizers. The molded article molded from this vinyl polymer has excellent weather resistance, and is improved in that the strength is reduced and the coloring is improved. Further, the vinyl polymer can be suitably used as a sealing material in the fields of construction and civil engineering. Furthermore, vinyl polymers can also be used as processing aids, extenders, fillers, and the like for synthetic resins.

As described above, according to the method for producing a vinyl polymer described in detail in the embodiment, 2,4-diphenyl-4-
Using methyl-1-pentene, exceed 220 ° C and 350 ° C
Since the polymerization is carried out at the following polymerization temperature, it is possible to reliably obtain a vinyl polymer having an extremely small molecular weight having a weight average molecular weight of 5,000 or less. Moreover, the ratio of those having a double bond at the terminal, that is, a large vinyl polymer having an average value of the number of double bonds at the terminal of the vinyl polymer of 0.7 to 1.0 based on the number of molecules of the vinyl polymer Can be obtained.

Further, by performing the polymerization using a continuous stirred tank type polymerization vessel, the control of the polymerization is easier than in the case of using a tubular continuous tank type polymerization vessel, and the polymerization is maintained in a stable state. be able to.

Further, the vinyl copolymer produced by the method of the present invention can be efficiently produced as a graft copolymer by copolymerizing with a vinyl monomer.

[0026]

EXAMPLES Examples, production examples and comparative examples will be given below.
The embodiment will be described more specifically. In addition, each of the following
In the examples, “parts” means parts by mass, and “%” means mass%.
You. (Examples 1 to 8 and Comparative Examples 1 to 5) Equipped with an electric heater
Into a pressurized continuous stirred tank polymerization vessel with a capacity of 300 ml
-Filled with ethyl ethoxypropionate and the temperatures are listed in Table 1.
Temperature up to the indicated temperature
2.45 to 2.65 MPa (25 to 27 kg / cm ^Two)
Kept.

Next, while keeping the pressure of the polymerization vessel constant, the monomer mixture having the monomer composition shown in Table 1 was polymerized from the raw material tank at a constant supply rate (23 g / min, residence time: 12 minutes). Continuous supply to the vessel was started. Then, a reactant corresponding to the supply amount of the monomer mixture was continuously extracted from the outlet. Immediately after the liquid feeding, after the reaction temperature once decreased, a rise in temperature due to the heat of polymerization was observed. However, the polymerization temperature was maintained at a predetermined temperature shown in Table 1 by controlling the heater.

The time when the temperature became stable after the start of the supply of the monomer mixture was defined as the starting point of the recovery of the reaction solution, and the polymerization reaction was continued for the polymerization time shown in Table 1 from this point. The obtained reaction liquid was introduced into a thin film evaporator, and volatile components such as an unreacted monomer and a solvent were removed at 235 ° C. under a reduced pressure of 30 mmHg to obtain a liquid resin. As a result of gas chromatography analysis, unreacted monomers in the liquid resin were 0.5% or less.

Using tetrahydrofuran as a solvent,
The number average molecular weight (hereinafter abbreviated as Mn) and the weight average molecular weight (hereinafter abbreviated as Mw) of the vinyl polymer obtained by gel permeation chromatography (hereinafter referred to as GPC) in terms of the polystyrene equivalent molecular weight. The results are shown in Tables 1 and 2. In addition, the symbol in Table 1 and Table 2 represents the following meaning.

ST: styrene, BA: butyl acrylate, AMSD: 2,4-diphenyl-4-methyl-1-
Penten (α-methylstyrene dimer), DiT: di-tert-butyl peroxide, Mw: weight average molecular weight by gel permeation chromatography (GPC), Mn: gel permeation chromatography (G
PC), number average molecular weight, F (TDB): the number of double bonds at the terminal of the vinyl polymer, measured by GPC and nuclear magnetic resonance spectrum (NMR), based on the number of molecules of the vinyl polymer.

Incidentally, Comparative Example 5 in Table 2 is described in JP-A-3-11.
This is based on Example 5 described in Japanese Patent Publication No. 1405. The reason why the value of F (TDB) in Example 1 shown in Table 1 exceeds 1.0 is based on a measurement error.

[0032]

[Table 1]

[0033]

[Table 2] As shown in Table 1, in Examples 1 to 4, it was obtained by using 2,4-diphenyl-4-methyl-1-pentene and setting the polymerization temperature to be higher than 220 ° C and 350 ° C or lower. The weight average molecular weight of the vinyl polymer was extremely small at 5,000 or less, and the ratio of those having a double bond at the terminal was as large as 0.7 or more.

On the other hand, in Comparative Examples 1 to 4, since 2,4-diphenyl-4-methyl-1-pentene was not used, the weight average molecular weight of the vinyl polymer was as large as 7000 or more. In Comparative Example 5, 2,4-diphenyl-4-methyl-1-pentene was used.
Since the polymerization temperature was slightly lower at 200 ° C., the weight average molecular weight of the vinyl polymer was 8,300.

The technical ideas grasped from the embodiment will be described below. The method for producing a vinyl polymer according to any one of claims 1 to 4, wherein the polymerization temperature is not lower than 230 ° C and not higher than 350 ° C. According to this method, the effects of the invention described in any one of claims 1 to 4 can be reliably exhibited.

A vinyl polymer obtained by the method for producing a vinyl polymer according to any one of claims 1 to 4. When configured in this manner, the vinyl polymer has a very small molecular weight with a weight average molecular weight of 5000 or less. Further, since the ratio of the terminal having a double bond is large, a graft copolymer can be efficiently obtained when the vinyl polymer is copolymerized with a vinyl monomer.

A graft copolymer obtained by copolymerizing a vinyl polymer obtained by the method for producing a vinyl polymer according to any one of claims 1 to 4 with a vinyl monomer. . With such a configuration, a graft copolymer having a high graft ratio can be easily obtained.

[0038]

As described above, according to the present invention, the following effects can be obtained. According to the method for producing a vinyl polymer according to the first aspect of the present invention, it is possible to reliably obtain a vinyl polymer having an extremely small molecular weight having a weight average molecular weight of 5,000 or less and to have a double bond at a terminal. Can be obtained.

According to the method for producing a vinyl polymer according to the second aspect of the invention, the effects of the first aspect of the invention can be efficiently exhibited. According to the method for producing a vinyl polymer of the invention described in claim 3, claim 1 or claim 2 is provided.
In addition to the effects of the invention described in (1), the ratio of the obtained vinyl polymer having a double bond at the terminal can be increased.

According to the method for producing a vinyl polymer of the invention described in claim 4, the control of polymerization is easy and the effect of the invention described in any one of claims 1 to 4 is ensured. Can be demonstrated.

Claims (4)

[Claims] (1) 2,4-diphenyl-4-methyl-1-
A method for producing a vinyl polymer, comprising polymerizing a monomer mixture containing pentene and other vinyl monomers at a polymerization temperature of over 220 ° C. and up to 350 ° C. 2. The 2,4-diphenyl- in the monomer mixture
The content of 4-methyl-1-pentene is 1 to 20% by mass,
The method for producing a vinyl polymer according to claim 1, wherein the content of the other vinyl monomer is 80 to 99% by mass. 3. The vinyl polymer according to claim 1, wherein the average number of double bonds at the terminal of the vinyl polymer is 0.7 to 1.0 based on the number of molecules of the vinyl polymer. Or a method for producing a vinyl polymer according to claim 2. 4. The method for producing a vinyl polymer according to claim 1, wherein the polymerization is carried out using a continuous stirred tank type polymerization vessel.